Capt. Ryan P. Hall, Capt. Nicholas S. Whitlock, 1st Lt. Justin J. Wilkens and Senior Airman Julian S. Scholten of Hurlburt Field were killed Feb. 18 when their U-28A troop support aircraft went down near Ambouli International Airport in Djibouti.

Spatial disorientation, as explained in a news release from Hurlburt, “is the failure to correctly sense the position, motion or attitude of the aircraft or of oneself in relation to the surface of the earth.”

Investigators found that the plane, under Hall’s command, never lost control and there were no indications of mechanical malfunction, the news release said.

According to the accident report, the “MC” — or “mishap crew” — was making its landing approach when it was alerted by air traffic controllers to pull up and warned about a worrying “sink rate.”

It states the first warning was issued as the plane was coming in at about 1,600 feet when air traffic controllers noted “excessive decent rate occurring.”

A final warning to “pull up, pull up” was given “approximately four seconds prior to impact,” the report said.

“There are no indications the crew took any actions to control or arrest the descent rate and nose down attitude,” the report said. “The evidence demonstrates that the MC did not recognize the position of the aircraft and, as a result, failed to take appropriate corrective actions.”

The report states that weather conditions were ideal, but the landing would have necessitated the use of night vision glasses, which could have caused disorientation, the report said.

“With the use of NVGs the field of view is limited and depth perception is reduced. This reduction in visual clues could have caused the MC to have a false perception of their altitude, attitude and descent rate,” the report said. That “could have caused the MC to become spatially disoriented,” it said.

The plane’s crew was experienced and highly skilled, according to reports and comments made at a memorial held in the airmen’s honor Feb. 28 at Hurlburt.

The report said the aircraft’s pilot, who wasn’t identified, was considered to be a conservative pilot who took precautions above and beyond what were called for. Between deployments in 2011 and 2012, he had been upgraded to the position of evaluator pilot.

The co-pilot, the report said, “was known to be a very detail-oriented person” and “a highly regarded officer and a real stand-up individual.”

“The (co-pilot) was known to be very engaged in the flight, even when not at the controls,” it said.

The report notes no medical issues for either the pilot or co-pilot, and indicates they were well rested before flying the uneventful combat mission on the night of the crash.

However, it did note that the mission pilot had recently undergone a drastic change in his daily routine and, on the day before the fatal accident, had taken ambien “as an adjunct to the aircrew fatigue management program.”

Two crew members had also just arrived at the base in Africa, the report said.

“While this is not likely incapacitating, it is possible that fatigue could have delayed a necessary response in a situation where a time-critical decision had to be made,” the report said.

Capt. Ryan P. Hall, Capt. Nicholas S. Whitlock, 1st Lt. Justin J. Wilkens and Senior Airman Julian S. Scholten of Hurlburt Field were killed Feb. 18 when their U-28A troop support aircraft went down near Ambouli International Airport in Djibouti.

Spatial disorientation, as explained in a news release from Hurlburt, “is the failure to correctly sense the position, motion or attitude of the aircraft or of oneself in relation to the surface of the earth.”

Investigators found that the plane, under Hall’s command, never lost control and there were no indications of mechanical malfunction, the news release said.

According to the accident report, the “MC” — or “mishap crew” — was making its landing approach when it was alerted by air traffic controllers to pull up and warned about a worrying “sink rate.”

It states the first warning was issued as the plane was coming in at about 1,600 feet when air traffic controllers noted “excessive decent rate occurring.”

A final warning to “pull up, pull up” was given “approximately four seconds prior to impact,” the report said.

“There are no indications the crew took any actions to control or arrest the descent rate and nose down attitude,” the report said. “The evidence demonstrates that the MC did not recognize the position of the aircraft and, as a result, failed to take appropriate corrective actions.”

The report states that weather conditions were ideal, but the landing would have necessitated the use of night vision glasses, which could have caused disorientation, the report said.

“With the use of NVGs the field of view is limited and depth perception is reduced. This reduction in visual clues could have caused the MC to have a false perception of their altitude, attitude and descent rate,” the report said. That “could have caused the MC to become spatially disoriented,” it said.

The plane’s crew was experienced and highly skilled, according to reports and comments made at a memorial held in the airmen’s honor Feb. 28 at Hurlburt.

The report said the aircraft’s pilot, who wasn’t identified, was considered to be a conservative pilot who took precautions above and beyond what were called for. Between deployments in 2011 and 2012, he had been upgraded to the position of evaluator pilot.

The co-pilot, the report said, “was known to be a very detail-oriented person” and “a highly regarded officer and a real stand-up individual.”

“The (co-pilot) was known to be very engaged in the flight, even when not at the controls,” it said.

The report notes no medical issues for either the pilot or co-pilot, and indicates they were well rested before flying the uneventful combat mission on the night of the crash.

However, it did note that the mission pilot had recently undergone a drastic change in his daily routine and, on the day before the fatal accident, had taken ambien “as an adjunct to the aircrew fatigue management program.”

Two crew members had also just arrived at the base in Africa, the report said.

“While this is not likely incapacitating, it is possible that fatigue could have delayed a necessary response in a situation where a time-critical decision had to be made,” the report said.